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Post by allanuk on Jan 5, 2015 12:35:33 GMT
Its nice to find these old forgotten captures from early days. It shows how much we have progressed.
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Post by BillW on Jan 5, 2015 21:17:13 GMT
Hi, Indeed, I was a bit confused as to why I had a folder marked "meteor spectrum" on the PC in question. However it was good to see some progress has been made. ...and in the way of progress, to save me re-typing the same stuff, I've put some more Quadrantid material on the BAA website which I should have put on here first. I hang my head in shame but I am getting lazy in my old age!  Check out britastro.org/node/6150#comment-1575I think this is pretty cool. It really is close to front line meteor science and initially I didn't think it would be possible to do such things with the watecs.  Great big colourful spectra from wee crappy ones do grow...  I will post the stuff here in due course, maybe next weekend, as I'm busy for the rest of the week. cheers, Bill. |
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Post by BillW on Feb 4, 2015 21:26:30 GMT
Hi, Caught a nice fireball last night/this morning (depnding on ones point of view )    cheers, Bill. |
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Post by allanuk on Feb 4, 2015 21:47:22 GMT
Good capture Bill. I assume the spectral lines are always offset to one side of the meteor train. That must make detection even more difficult.
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Post by BillW on Feb 4, 2015 23:03:25 GMT
Yes, Thats the way diffraction gratings work. It's a subtle idea but since meteors are generally "skinny" they act as their own slit. So the grating diffracts this "slit" image through an angle proportional to the number of grooves and wavelength thus generating the spectrum.
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Post by stewartw on Feb 5, 2015 8:32:13 GMT
Hi Bill,
Nice one.
How accurate is the timestamp? Ravensmoor North detected a bright meteor through cloud 61 seconds earlier that what your timestamp suggests.
Cheers
William
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Post by BillW on Feb 5, 2015 9:20:38 GMT
Hi,
These are older un networked PC's, I reset the machines at the start of the evening but it could be several seconds.
I don't think it'd be as much as 61 secs though.
The sodium emission is strong, starts before anything else appears. Not quite sure what that means yet but very noticable.
cheers,
Bill.
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Post by stewartw on Feb 5, 2015 12:20:16 GMT
Hi Bill, Hi, These are older un networked PC's, I reset the machines at the start of the evening but it could be several seconds. I don't think it'd be as much as 61 secs though. I'll upload the composite image when I get home tonight. Did the meteor happen to be to your south or where you facing north to avoid the glare of the moon? Cheers William |
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Post by BillW on Feb 5, 2015 13:41:12 GMT
I was well round to the north, Az ~35 deg Alt ~30 deg. The three brightest stars to the right are the handle of the Plough.
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Post by stewartw on Feb 5, 2015 14:12:25 GMT
Hi Bill,
No chance then that I would have caught it ... though I do know of a certain gentleman to your north who will soon be deploying a 3.8mm f0.8 which should cover that part of the sky :-)
Cheers
William
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Post by BillW on Feb 5, 2015 16:04:26 GMT
That would be most useful! :-)
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Post by BillW on Mar 17, 2015 16:40:29 GMT
Hi, Not much in the way of clear sky recently. Had a few hours over the weekend. Caught this spectrum.  It was quite faint but what is interesting is the brightness of the OI line at 557.7nm. This is a "forbidden" transition from oxygen in the atmosphere. Usually only seen on fast meteors that ablate higher than average, ~100km + up. It is only at this height the conditions allow the oxygen atoms to stay excited long enough to emit the meta stable photons ( lifetime 0.74 seconds) before losing the energy through collisions. The glow from this emission decays rapidly but a few "lifetimes" is a couple of seconds. the train was still fading when the video cut out after 40 frames, about 1.5 seconds. So this was probably coming at us head on (0508UT) , very fast and ablated fairly high up. cheers, Bill. |
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Post by allanuk on Mar 17, 2015 19:03:05 GMT
Good catch Bill.
I appreciate the informative description of events. It helps me to understand what I'm seeing.
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Post by BillW on Mar 17, 2015 20:39:04 GMT
Cheers Alan, This is one reason why I really like presenting the spectra as the synthetic colour versions.
A standrd graphical spectrum just wouldn't have had the same impact or conveyed the colour information.
I meant to add that this colour is the same as the green tint in the aurora and it happens at the same altitude for the same quantum physics reasons!
Absolutely brill!
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